Pitman or like machine element



June 13, v1 S39. c. .1. HUDSON u I PITMAN OR LIKE MACHINE ELEMENT Filed Aug. 1o, 1938 www Patented June 13, 1939 UNITED STATES .9ATENTA OFFICE Application August 10,

6 Claims.

This invention relates to machine elements such as pitmans and more particularly to pitmans constructed or equipped to counterbalance the weight of associated machine elements.

Although machine elements embodying the invention may be used advantageously in machines of various kinds, they may be used to particular advantage in pumping machinery, for example,

such as is used in the oil fields. Oil well pumps generally include a heavy pump rod connected to one end of a walking beam and a pitman connected to the other end of the walking beam and to a crank. The weight of the pump rod frequently is so great that counterweights have been applied to the walking beam to relieve the pumping machinery of the recurrent load pulsations resulting from lifting the pump rod. I

have found that the strain on the pumping machinery can be eliminated still further by pro viding a weight for counterbalancing the pump rod and positioning the weight on the pitman adjacent the crank so that the inertia of the weight, moving in a substantially continuous orbital path, creates a ily-wheel effect which prevents the pulsating shocks inherent in counterbalancing arrangements heretofore provided.

Accordingly, one object of the invention is to provide a mechanism including a pitman and a counterweight positioned on the pitman close to its crank-connected end.

Another object is to provide a pitman or the like element equipped with a counterweight and in which a simple and positive interconnection between the element and the counterweight is provided..

A further object is to provide a pitman or like element including spaced arm parts and a weight device adapted to perform the dual function of providing a desired counterbalancing effect and at the same time reenforcing the spaced arm parts.

Other objects will become apparent from a reading of the following description, the appended claims, and the accompanying drawing, 45 in which:

Figure 1 is a view showing a pitman embodying the invention and as it may be used in one kind of pumping machinery, only parts of which are shown;

Figure 2 is a front elevational view of a pitman embodying the invention, drawn on an enlarged scale as compared to Figure 1;

Figure 3 is a partial longitudinal section taken on the line 2 2 of Figure 4;

Figure 4 is a View in edge elevation, and

1938, Serial No. 224,158 (Cl. 'M -589) Figure 5 is a detail View in elevation showing a combined balancing Weight and reenforcing member.

Referring to Figure 1, a pitman A is shown connected at one of its ends to a cra'nk B and at 5 its other end is equipped with a stirrup C providing connection to one end of a walking beam D mounted to rock on a Sampson post E, the other end of the walking beam being connected to the usual pump rod F. The pitman includes spaced end blocks I-2 connected by an elongated body part or arm generally designated 3 and comprising spaced parts or straps 4 and 5 secured to the blocks I and 2 by means of bolts Ii and I respectively.

The block I is provided with a rectangular opening 8, one end of which is formed with a semicircular seat 9 for receiving a bushing or babbitting (not shown). A movable seat member IIJ is mounted for adjustment within the rectangular opening 8 and is formed With an inclined face I2 adapted to cooperate with a correspondingly inclined face on an adjusting wedge I3 adapted to be drawn into adjusted position by means of a screw I4 for holding the bushing or bab-bitting in place. The block I serves to 'connect the" pitman to the crank arm B. The block 2 is sho-wn as being provided with a plurality of apertures I5 which provide for connection of the pitman to the stirrup C. o

In accordance with my invention, a desired balancing of the pitman, or counterbalancing of the pump rod is obtained through the provision of a weight generally designated I6 which is mounted on the arm 3. In the preferred em- 3f bodiment of the invention, two weights designated I'I and I8 are shown, and it will be understood that these two Weights together constitute the weight or means for effecting the desiredbalance of the pitman and counterbalancing o'f the pump rod. The weight Il comprises a body part I Ia which is adapted to be fitted between the arm parts 4 and 5, and lugs I'Ib which extend from both edges and at each end of the Weight so as to lie alongside the strips 4 and 5; The opposite ends of the body part I'Ia (included between adjacent lugs I'Ib) are inclined and parallel. This facilitates positioning of the weight I'I on the arm with the body I'Ia included between the arm parts 4 and 5 and with the lugs I'Ib lying alongside the parts 4 and 5 respectively. 'I'he weight II is positioned on the arm 3 by rst inserting it between the straps 4 and 5 as indicated at (a) in dotted lines in Figure 3 and then tilting it, in the direction of the arrows .r and y, 55

through the dotted line position (b) and finally to the position shown in full lines in Figure 3. The inclination of the ends of the body part Ila permits this tilting movement insertion, and also results in the outermost edges of the inclined ends of the body IIa being disposed close to the associated arm parts 4 and 5 when the weight has been moved to its nal position.

The weight IB is similar in construction to the weight lla, comprising also a body part I8a and lugs |811. The weight I8 may be positioned on the arm 3 in a manner similar to that described with reference to the positioning of the weight l1. For maintaining the weights in place, set screws I9 and 20 are extended through apertures 2| formed in the arm part 5 so as to bear respectiVely against the weights l1 and i8.

Preferably, when using two Weights, they are positioned in abutting relation with the ends of the weights adjacent the arm 5 extending towards opposite ends of the arm and sloping away from the adjacent arm part 5, as shown most clearly in Figure 2. As a result of this arrangement, the set screws I9 and 20, acting on the inclined ends of the weight bodies, will tend to force the weights together and prevent their separation, thereby maintaining them securely in place on the arm. It will be understood that the number or size of the weights used will depend upon the balance required, and that the weights will act to reenforce and strengthen the arm structure as well as to counterbalance the weight of the pump rod.

The embodiment of the invention disclosed herein is a practical and the now preferred form, but Various changes may be made in the construction and relative arrangement of the parts without departing from the invention as donned in the claims.

I claim:

1. In a movable machine element, an arrn comprising spaced substantially parallel parts; and a balancing weight including a body removably positioned between said spaced arm parts, and lugs protruding respectively from each side and at each end of said body and lying alongside the edges of said spaced arm parts, the body part and lugs being so proportioned relative to spaced arm parts, and the ends of the body part included between said lugs being so formed and proportioned as to permit angular' or tilting movement of said weight in the direction of extent of said arm to facilitate removal or" the weight, the body part yet having portions lying close to the respectively vassociated adjacent spaced arm parts when the weight is in operative position.

2. In a movable machine element, an arm comprising spaced substantially parallel parts; and

a balancing weight including a body removably positioned between said spaced arm parts, and lugs protruding respectively from each side and at each end of said body and lying alongside the edges of said spaced arm parts, the ends of the body part included between said lugs being inclined in the direction of extent of said arm and substantially mutually parallel.

3. In a movable machine element, an arm; a pair of balancing weights mounted on said arm; and separate means carried by the arm at points spaced longitudinally thereof and associated separately and respectively one only with each weight for urging the weights together and resisting their separation longitudinally of the arm.

4. In a movable machine element, an arm comprising spaced substantially parallel parts; two balancing weights mounted on said arm and between said spaced arm parts, the ends of each weight being inclined in the direction of extent of said arm and substantially mutually parallel, the ends of one weight being inclined reversely to the ends of the other weight, the two weights being in abutting relation with two adjacent ends extending towards opposite ends of the arm and sloping away from the adjacent arm part; and set screws extending through said adjacent arm part and bearing against said last named ends, thereby urging said weights together.

5. In a movable machine element, an arm compris-ing spaced substantially parallel parts; two balancing weights mounted on said arm, each of said weights including a body positioned between said spaced arrn parts and lugs protruding respectively from each side and at each end of said., body and lying alongside the edges of said spaced arm parts, the ends ofthe body part intervening between said lugs being inclined in the direction of extent of said `arm and substantially mutually parallel, the body ends of one weight being inclined reversely to the body ends of the other weight, the two weightsbeing in abutting relation with two adjacentbody ends extending towards opposite ends of the arm and sloping away from theadjacent arm part; and set screws extending through said adjacent arm part and bearing against said last named body ends, therebyvurging said weights together.

6. In a pitman, spaced connecting block members formed with parallel apertures for affording connection respectively toAother machine elements; a pitman arm structure comprising spacedl straps extending between and connecting saidv block members; and a combined balancing weight and reenforcing member secured to and between said straps intermediate the connection of the straps to the blocks.

CHARLES J. HUDSON. 

